[C]+[T]+[Spacebar] : Free items
[F8] : Some funny stuff.
[G]+[O]+[D] : God Mode
[Shift]+[Tab] : End level
Add to the commandline (for series 1-4):
(This also removes various delays and nagscreens)
Then, in the game, use [F10]+ some letter keys :
[W] Warp to level [E] Restart
[T] Sprite test [Y] Mess up sprites
[I] Free items [S] Toggle slow motion
[D] Record demo [G] Toggle God mode
[J] Toggle jump cheat [C] Stats
[V] Add VLB's [N] Toggle clipping
[M] Memory usage
You may also try adding TEDLEVEL, COMP, NOCOMP.
In the "Pyramide of moons" get the yellow gem and
open the door then get all of the 12 worms in one
place and they will turn into
a foot climb the foot and enter the secret level.